Rotary percussion apparatus



Nov. 25, 1969 J. R. SIDDONS ETAL 3,480,089

ROTARY PERCUSSION APPARATUS 3 Sheets-Sheet 1 Filed July lO, 1967 NOV. 25, 1969 R 5|DDON5 ETAL 3,480,089

ROTARY PERCUSSION APPARATUS 'Filed July 10, 1967 s sheets-sheet 2 /afm Nov. 25, 1969 J. R. slDDONS ET AL 3,480,089

ROTARY PERCUSSION APPARATUS Filed July 10, 1967 3 Sheets-Sheet 'v5 United States Patent O 3,480,089 ROTARY PERCUSSION APPARATUS John Royston Siddons, Lower Plenty, Victoria, and Kenneth Gordon, Heidelberg, Victoria, Australia, assiguors to Siddons Industries Limited, Carlton, Victoria, Australia, a Victorian company Filed July 10, 1967, Ser. No. 652,273 Claims priority, application Australia, July 15, 1966, 8,361/ 66; Feb. 27, 1967, 18,202/67; .lune 8, 1967, 22,912/ 67 Int. Cl. B25d 9/04; E21c 3/08 U.S. Cl. 173--99 10 Claims ABSTRACT F THE DISCLOSURE Rotary percussion apparatus comprising a tool bit nonrotatably mounted in a rotatable sleeve driven by a motor, the tool bit being operatively driven by a rotor driven by the motor, the rotor comprising a pair of spaced disks, the inner confronting surfaces of which are formed with complementary track portions which together form a track adapted to receive striker means movable along the track during rotation of the rotor for driving the tool bit.

This invention relates to rotary percussion apparatus for imparting a hammering action particularly in power tools such as rock and masonry drills, chisels and the like, in power tools for driving pins, studs and other fasteners into steel, concrete or other relatively hard material, in pile drivers and in other apparatus wherein a relatively high speed percussive action is required. The rotary percussion apparatus comprises rotor means having at least one track for accommodating the striker means of the apparatus, the track extending outwardly in opposite directions from the axis of rotation of the rotor means and the striker means being movable along the track such that on rotation of the rotor means the striker will be driven outwardly towards an end of the track to a position whereat it will hit an operating member-such as a drill bit of a masonry drilland then rebound to the opposite end part of the track by the time the rotor means has turned a suicient extent for the striker to then be in position to hit the operating member again. This rotary percussion apparatus may be readily incorporated in any one of a wide variety of tools or apparatus.

One object of this invention is to provide rotary percussion apparatus, comprising a rotary member having means for imparting a hammer blow to an associated operative member at least once each rotation of the rotary member, which will be of relatively simple and unexpensive construction, which may have a wide range of practical applications and which will be of high eiciency 1n use.

Another object of the invention is to provide rotary percussion apparatus comprising a rotor and striker means carried by said rotor wherein the rotor has means for transferring the striker means between two different operative portions so that the striker means will be operative to apply hammer blows at two different locations in the perimeter of the rotor during rotation of the rotor.

A further object is to provide rotary percussion means comprising a rotor, track means in said rotor and Striker means mounted for travel in said track means, wherein the track means is so arranged that on rotation of the rotor the striker means will be moved to an operative position and on actuation of the striker means said striker means will move to a different operative position ready for operation.

Yet another object of the invention is to provide rotary hammer apparatus comprising a rotor and striker means associated with the rotor so as to be adapted to actuate an operating member such as a masonry drill, chisel or the llke, wherein the rotor has means for moving the striker means to at least two different positions in its periphery whereby the striker means will be effective to hammer the operative member at least twice in each rotation of the rotor.

A still further object is to provide rotary hammer apparatus having striker means adapted to apply at least two percussive blows to an operating member such as a masonry drill, chisel or the like each rotation of the rotor.

It is another object of the invention to provide improved means for applying a high speed hammering action to an end of a rotary masonry drill or chisel, a fastener such as a pin, stud or the like, or to other member adapted to be actuated by the application thereto of high-speed hammerlng action.

A further object is to provide an improved power tool of the nature of a masonry drill or chisel.

A still further object is to provide a new type of power tool for driving fasteners such as studs, pins and the like into concrete, steel or other hard material.

Preferably, the rotor means provided by the invention consists of two somewhat discoid members adapted to be fastened together in spaced relationship so that an end of the operative member can project within the space between the peripheral portions of the somewhat discoid members, and at least one track consists of opposed complementary track portions formed in the inner surfaces of the two somewhat discoid rotor members. The rotor may be made of metal-as hardened steel-or of a tough synthetic plastic material such as polycarbonate or nylon, and the discoid members may incorporate integral spacer means through which may be fitted bolts for fastening together the two rotor members.

In the preferred form of the rotor the track is of somewhat S-shape (that is to say, a curve consisting of two curved portions in continuous reverse bend arrangement and with the opposite ends thereof extended, preferably arcuately) arranged so that the centre-line of the track passes through the axis of rotation of the rotor, and it is preferred that the striker means be a spherical ball adapted to roll freely along the track from one end to the other. The S-shaped track may consist of two semicircular track parts in reverse-bend arrangement, the inner end of one semi-circular track part being contiguous wtih the inner end of the other semi-circular track with arcuate extensions of the outer ends thereof, the radius of curvature of the arcuate extensions being twice that of the semi-circular track parts.

Thus, upon rotation of the rotor the ball will be driven to one end of the track, when it will hit the end of the operative member projecting between the discoid members so as to drive that member linearly, the ball will then rebound and travel to the other end of the track during one-half a revolution of the rotor so as to be in position to again hit the end of the operative member.

In the application of the rotary percussion apparatus to a masonry drill, for example, the rotoi means may be mounted in suitable bearings in a housing having means for engagement therein of one end of a drill bit, and said housing will incorporate a motor-such as an electric motor-and drive gearing from the motor to the rotor means, so that upon operation of the motor the rotor will be driven at a desired speed to cause the striker means therein to apply blows to the inner end of the drill bit at a desired rate. There may also be provided drive means for rotating the drill bit. If desired there may be incorporated an intermediate member for transmitting the percussive blows from the percussion member of the rotor to the drill bit.

If desired, two or more of the rotors may be arranged in tandem for rotation about the same axis, so as to be operative to apply blows to an operative member or operative members either simultaneously (or substantially simultaneously) or in arcuately timed relationship.

In the application of the rotary percussion apparatus to a tool for driving studs, pins or other fasteners into steel, concrete or other masonary walls the rotor may be mounted in a frame arranged so that the striker member will apply hammer blows directly to the end of the fastener when said fastener is correctly in position in the tool and said tool has been placed in position for the application of the fastener to the solid structure into which it is to be driven, or said tool may be so constructed that the striker member engages with an intermediate or piston member and said intermediate member is adapted to act upon the fastener. Automatic feed means may be incorporated to provide for a continuous feed of fasteners into operative position in said tool.

In order that the invention may be clearly understood and readily put into practical form reference will now be made to the accompanying illustrative drawings which depict one exemplary construction of rotary percussion apparatus incorporated in a power tool made according to the invention, and a minor modification. In these drawings:

FIG. 1 is a longitudinal cross-section through the head portion of a power tool for use in drilling concrete or like purposes said power tool incorporating the rotary percussion apparatus of this invention;

FIG. 2 shows a cross-section on the plane and in the direction indicated by the line and arrows 2 2 of FIG. 1;

FIG. 3 is a cross-section on the plane and in the direction indicated by the line and arrows 3 3 of FIG. l;

FIG. 4 is a cross-section on the plane and in the direction indicated by the line and arrows 4 4 of FIG. 1;

FIG. 5 shows part of the rotor and the piston, and is a cross-section on the line and in the direction indicated by the line and arrows 5 5 of FIG. 4;

FIG. 6 is a transverse cross-section on the plane and in the direction indicated by the line and arrows 6 6 of FIG. 1;

FIG. 7 illustrates, in perspective view, one part of the two-piece rotor;

FIGS. 8 to 12 are diagrammatic views illustrating the travel of the piston as the rotor completes one-half of a turn, and the operation of the rotary hammer;

FIG. 13 shows the calculated absolute path of the piston; and

FIG. 14 illustrates a modied design of piston.

The power tool illustrated in these drawings includes a frame or housing which, as shown, consists of several parts designated by the reference numerals 21, 22, 23 and 24. The main housing part 21 has seatings for bearings 25 for a lmain drive shaft 26 from an electric motor 27 mounted in the housing part 23, which is shaped to provide a handle 28 having mounted therein a triggertype switch 29. The housing part 24 constitutes a cover for one side of the main housing 21. In the main housing part 21 and the cover 24 are bearings for the pintles for the rotor, and in the housing part 22 and cover 24 are bearings for a transverse and an intermediate shaft carrying part of the driving gears.

Detachably fastened to the housing 22 is a secondary housing 31 for supporting a tool bit A, such as a concrete or masonry drill, a chisel and so on. The main housing part 21 has a seating 32 for a bearing 33 in axial alignment with that secondary housing 31.

The rotor provided by this invention consists of two parts 34 and 35 which are detachably fastened together by bolts 36, which also fasten in position a lirst plate 37 having an integral pintle 38, a second plate 39 having an integral pintle 40 and a spur-gear 41. The two pintles 38 and 40 are journaled in aligned bearings 42, and a further pair of aligned bearings 43 support a transverse shaft 44 with its axis parallel to the axis of rotation of the pintles 38, 40. Fastened to the shaft 44 is a spur gear 45 in mesh with the spur gear 41 and a worm or a helical gear 46.

The main drive shaft 26 has a fan 48 adjacent the motor 27 and at the other end is a bevel gear 49 which is in mesh with a bevel gear mounted on an intermediate shaft 51. Also on the intermediate shaft is a spur gear wheel 52 which meshes with the spur gear 45 so as to impart a drive at a desired predetermined speed from the motor 27 to the gear wheel 41 and thus to the rotor parts 34, 35.

Rotatably mounted in the bearing 33 is a Sleeve 54 having an external ange 55 supporting a friction pad 56. A gear wheel 57 is rotatable on the sleeve 54 so as to be in mesh with the worm or helical gear 46 and it is pressed firmly against the friction disc 56 by a spring 58 seated on a member 59 constituting part of the support for a bearing 70 mounted at the inner end of the front housing 31. Engaged in the inner end of the sleeve 54 is a bush 62 having a non-circular axial hole of a size and shape to receive non-rotatably the inner end part 63 of the tool bit A. Said tool bit A has a circumferential groove 64 releasably engaged by a retainer 65 as shown in FIG. 6. That retainer is mounted for lateral sliding movement in the front housing 31 and when it is pushed inwardly, in the direction of the arrow B in FIG. 6, the tool A may be withdrawn from its engagement in the front housing 31 and bush 62. The retainer 65 is adapted to engage the groove 64 when it is moved outwardly in the opposite direction, and the groove is of such width that the tool A may move longitudinally through a small distance. A spring-pressed ball 66 is operative to hold the retainer 65 in position.

Slidably mounted in the sleeve 54 is an intermediate impact member 67 having a resilient ring 68 at a midposition. Said impact member 67 is adapted to impart blows to the inner end of the tool A when its inner end is hit repeatedly at high speed by the piston member of the rotor, and the inner end part of said impact member is provided with two parallel flats 69, as shown in FIGS. l, 4 and 5.

By reason of the drive arrangement described the motor 27 is adapted to drive the gear 57 which in turn will impart a drive through the friction disc 56 to the sleeve 54 and tool A. It is apparent that if the tool A should jam, and be held against turning, the gear 57 will slip relative to the sleeve 54.

Each of the rotor parts 34, 35 has in its inner side a track of somewhat S-shape, as shown particularly in FIGS. 5 and 7, and two spacer members 71. The bolts 36 t through holes in the rotor parts arranged so that the bolts pass through the spacers 71, and said spacers are of such length that the general planes of the inner surfaces of the rotor parts 34, 35 are spaced apart a distance to accommodate the inner end of the impact member 67 that part having the flats 69 in such manner that the impact member 67 will be held against rotation but there will be no appreciable restriction on the linear movement of the impact member or the rotation of the rotor parts 34, 35.

The track 70 in each of the rotor parts 34, 35 has, in cross-section, two arcuate faces 73 separated by a channel portion 74, and the arcuate faces 73 of the two parts 34, 35 are so formed that at any cross-section the arcs are on a common circle so that a spherical piston member or striker ball 75 may be conveniently mounted for travel along the track 70. As shown in FIG. 5 the S-shaped track 70 of each rotor part 34, 35 passes through the middle part of the rotor part, the centre-line of the track passing through the axis of rotation of the rotor part. The opposite end portions of the track 70 are arcuate and the centre of curvature of said end portions is coincident with the axis of rotation of the rotor. The intermediate portions of the track between each of the opposite end portions and the axis of rotation are semi-circular in shape, and they are arranged as a reverse bend. The radius of curvature of said semi-circular track portions is one-half that of the arcuate end portions and the centre of curvature of each coincides with the centre-line of the adjacent hole for reception of a fastening bolt 36. The arcuate extent of each of said arcuate end portions of the track is approximately 90.

The spherical ball 75 can travel from one end of the track to the other, passing through the axis of rotation of the rotor in its travel.

The operative parts of the tool are so arranged that the central axis through the impact member 67, in the direction of its linear travel, is substantially tangential to the centre line of the arcuate end portions of the track 70 and, therefore, adapted to coincide with the centre of the spherical ball 75 at one part of its travel.

When the composite rotor is caused to rotate at high speed the ball 75 is caused to travel to one of the outer end portions of the track 70. The relationship of the rotor and impact member is as shown in FIG. 5, and the direction of rotation of the rotor is as shown by the arrow C in FIG. 5, such that the ball 75 will travel towards and strike the inner end of the impact member 67, to cause said member y67 to move in the direction of the arrow D and the ball 75 to rebound in the direction of arrow E (see FIG. 8).

The ball 75 and impact member 67 are made of steel and the coeicient of restitution is such that, as the rotor continues to rotate, the ball 75 travels back along the track towards the axis of rotation of the rotor, as shown in FIG. 9, against the influence of centrifugal and dynamic forces. The force with which it is driven in the direction of the arrow D is such that the ball travels past the axis of rotation, at which stage its momentum is increased by reason of centrifugal force, and it is then caused to travel outwardly at a high speed towards the opposite end of the track, as shown in FIG. l0. In its initial rebound travel the ball 75 travels in a direction opposite to that of the direction of rotation of the rotor but as can be seen from FIGS. l0 to 13 the ball 75 travels in the same rotary direction as the rotor after it has passed the axis of rotation of the rotor. Thus, the speed of travel of the ball is a composite of its own speed relative to the rotor and the speed of travel of the rotor. In normal operation the travel of the ball 75 from one end portion of the track to the other is effected during a 1half-rotation of the rotor, so that the ball 75 is nearing that opposite end of the track as that end of the track is approaching the end of the impact member 67. Said impact member, in that interval of time, will have rebounded*as indicated by the arro-w F in FIG. ll-so that its inner end will be in position to be again struck by the ball 75 when the rotor has completed one-half a turn-see FIG. l2.

The rebound of the impact member is due partly t0 the hardness of the material into which the tool A is being driven. If the tool encounters material of less hard character the rebound of the tool will be lessened and therefore the ball 75 may hit the inner end of the impact member 67 a little later in its travel than would normally be the case, and in the next travel of the ball 75 it may be a little late in arriving at its posi tion to again strike the impact member 67. Thus, the ball 75 need not strike the impact member at all times in the same position on its arcuate travel.

As the rotor 34, 35 is turning about its axis as the striker ball 75 travels along the track it is believed that theoretically said ball travels in an absolute path as illustrated in FIG. 13. The path may vary according to the location of the inner end of the impact member at the time it is struck by the ball 75 and the coecient of restitution of the ball.

By way of example only the dimensions and speed of rotation may be:

Overall diameter of rotor-3%" Ball-l" diameter, made of steel Speed of rotation-1625 revs./minute We believe that the operation of the striker ball in the rotor is independent of speed of the rotor and/or ot' the mass of the ball.

It is believed to be advantageous, for the life of the impact member 67, for the inner end of that member to be made concave, with a groove 77 extending diametrically of the end of that member-See FIGS. 4 and 5.

The modification shown diagrammatically in FIG. 14 has an articulated piston member 79 made for sliding movement in the track 70, instead of rolling movement. The opposite ends of the member 79 may be somewhat convex.

The rotor may be made any desired diameter and it may be driven at any suitable speed, depending to an extent upon the speed of the hammering action required. The shape of the track may be varied, we believe, though we have found the S-shape track provides for very eicient operation.

In some cases it may be necessary to provide spring means to ensure that the inner end of the tool bit A is normally held in its innermost position in the sleeve, and it may be desirable to eliminate the impact member 67 (when the ball 75 would strike directly on the inner end of the tool bit A). It will also be realised that teh diameter of the rotor may be increased or decreased to provide for any required power output, as may be the diameter of the striker ball 75. Consideration has also been given to the provision of a stop at the middle part of the track 70 and to use two striker balls, so that each ball will operate once in each complete turn of the rotor. In such an arrangement it may be necessary to incorporate means for buffering the ball (to stop its travel) at the inner end of each part of the track-as by providing for a short sealed part or pocket at the inner end of the track wherein air would be trapped to buffer the action of the ball.

The main feature of the invention resides in the principle of operation of the rotary percussion apparatus or hammer, as herein disclosed, and we believe that such a rotary hammer may be incorporated in many other types of apparatus, depending largely upon the size of the rotor, the size of the striker ball, and the speed at which the rotor is driven. By way of example we state that we believe the principle of operation of a rotary hammer as herein disclosed may be incorporated in a pile driver, or in a tool for driving fasteners into concrete, steel or other hard material. Such tools as at present made usually utilize explosive material-such as gunpoWder-but we believe the rotary hammer of this invention could be utilized in such a tool.

It will be appreciated that there may be made modilications in details of design or of construction other than those mentioned above and that the rotary percussion apparatus provided by this invention may be applied to a wide range of tools and other apparatus. Thus, the scope of the invention is to be limited only by the ambit of the appended claims.

What is claimed is:

1. Rotary percussion apparatus comprising a housing, motor means, rotatable sleeve means mounted in said housing, drive means operatively connecting said sleeve means and said motor means for rotating the former, a tool bit non-rotatably carried by said sleeve means for rotation therewith, a secondary housing mounted on said first mentioned housing in coaxial alignment with said rotatable sleeve and housing the same, said drive means being mounted in said secondary housing and including a gear wheel rotatably mounted on said sleeve, friction clutch means operatively connecting said gear ywheel and said sleeve, rotor means mounted in said housing having at least one track extending radially outwardly in opposite directions from the axis of rotation of said rotor means, said rotor means being operatively connected to said motor means for rotation thereby, an impact member operatively disposed between said rotor means and said tool bit, and striker means movable along said track, said striker means being operative on rotation of said rotor means to apply blows to said impact member thereby to drive said tool bit.

2. The apparatus of claim 1 -wherein said striker means is a spherical ball.

3. The apparatus of claim 1 wherein said rotor means consists of a pair of disks adapted to be fastened together in spaced relation to receive between them a flattened end portion of said impact member.

4. The aparatus of claim 3 wherein said discoid members have opposed complementary track portions formed on their inner, facing surfaces, each track being substantially S-shape and having its approximate center passing through the axis of rotation of said rotor means.

5. The apparatus of claim 4 wherein said S-shaped track consists of two semi-circular track portions in reverse bend arrangement, the inner ends of said semi-circular track portions being contiguous, and two arcuate track portions extending from the opposite ends of the semi-circular track portions, the radius of curvature of each of said arcuate track portions being approximately double the radius of curvature of said semi-circular track portions.

6. Rotary percussion apparatus comprising a housing, motor means, rotatable sleeve means mounted in said housing, drive means operatively connecting said sleeve means and said motor means for rotating the former, a tool bit mounted within said housing for longitudinal movement relative thereto and nonrotatably carried by said sleeve means for rotation therewith, rotor means cornprising a pair of spaced disks, said disks being formed on the inner, confronting surfaces thereof with complemental track sections extending radially outwardly in opposite directions from the axis of rotation of said rotor means, said rotor means being operatively connected to said motor means for rotation thereby, and striker means movable along said track sections and operative on rotation of said rotor means to drive said tool bit, said track portions being formed so as to move said striker means into operative, striking position twice in each revolution of said rotor means.

7. The apparatus of claim 6 further including an impact member operatively disposed between said tool bit and said rotor means, said impact member being formed with a flattened end portion extending between said spaced disks in a direction tangential to the arcuate ends of said track portions.

8. The apparatus of claim 7 wherein each track portion is substantially S-shape having its approximate center passing through the axis of rotation of said rotor means, each S-shape track portion consisting of two semicircular track portions in reverse bend arrangement, the inner ends of said semi-circular track portions being contiguous, and two arcuate track portions extending from the opposite ends of the semi-circular track portions, the radius of curvature of each of said arcuate track portions being approximately double the radius of curvature of said semi-circular track portions.

9. Rotary percussion apparatus comprising rotor means, means for mounting said rotor for rotation, said rotor having a continuous track the center line of which passes through the axis of rotation of said rotor, striker means movable along said track, an impact member associated with said rotor means and engaged by said striker means during rotation of said rotor means to drive the impact member in a desired direction, said track being of substantially S-shape with the portions of track extending outwardly in opposite direction from said axis of rotation being in continuous reverse bend arrangement so that said striker means can travel from one end of said track to the other, the outer end portions of said track being arcuate in shape and concentric with said axis of rotation, said striker means moving into striking position in said track twice in each revolution of said rotor means, the radius of curvature of each of said arcuate track portions being approximately double the radius of curvature of said reversely bent portions of said track which extend outwardly from said axis of rotation.

10. Rotary percussion apparatus acocrding to claim 9 Iwherein each arcuate outer end portion of said track subtends an angle of approximately References Cited UNITED STATES PATENTS Re.2l,98l 12/1941 Vasard 173-98 1,632,937 6/1927 Wagner 173-98 1,812,692 6/1931 Georgevitch 173-99 2,248,523 7/1941 Francastel 173-98 2,500,402 3/1950 Craig 173-109 X FOREIGN PATENTS 60,804 12/1924 Sweden.

DAVID H. BROWN, Primary Examiner U.S. Cl. X.R. 173-109 

